The new contract is a change of direction for the brothers, who opened their latest pub The Cadogan Arms in May, as it is the first time they have provided a permanent food offering outside their own sites.
Food from the ETM-run kitchen will be served in The Lexington's downstairs lounge area from 12pm to 3pm and 5pm to 10pm Mondays to Fridays; 12pm to 11pm Saturdays and 12pm to 9pm Sundays. The menu will feature American classics and British dishes priced from £7 to £11.50 such as BBQ Ribs with BBQ Bourbon Sauce, fries and coleslaw and slow roasted belly of pork with mash, green beans and gravy.
A spokeswoman for The Lexington said the owners had no previous experience of providing food, but wanted to broaden the business' appeal to both existing customers and new ones, so approached ETM with the proposition.
"Before we started doing food it was never open at lunchtime, but there are lots of businesses along Pentonville Road, so it makes sense to provide workers with somewhere to go and there will be a higher number of students in the area come September, " she said.
"The Lexington's owners didn't have the contacts on the kitchen side of things, so they decided to call in ETM's expertise."